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Sunday, July 15, 2012

HST2012, CERN - Day 12

The first lecture was the continuation about Accelerators.We leaved the technical details and we got into the Physics: energy, number of events, luminosity, etc.

It was emphasized that in the LHC does not circulate a steady stream of protons, they are sent in bunches and compressed by existing dipoles and quadrupoles in the accelerator. The curvature and focal power we use in optics is applied here at the LHC in terms of the strength of the different magnets. The magnetic field created at the LHC is 8.33 T, in the Earth is situated between 24 mT and 66 mT. There are approximately 6000 magnets in the LHC.

The second lecture was about Antimatter, performed by Rolf Landua based on the movie Angels and Demons. Basically, we tried to respond to seven questions related to the subject: What is it? Where is it created? How is it created? What is the mystery behind this? How to study it? Can be used as energy source or a bomb? There antimatter in our day-to-day?

Antimatter is real and is composed of antiparticles. For example, the hydrogen atom is formed by a proton and an electron, in the version of the antimatter, antihydrogen consists of a positron and antiproton. Antimatter is created in the LHC, the LHCb is the detector for those particles.

To create antiprotons, LHC collide protons with cores of Iridium, copper, etc. .. Antiprotons are created, retarded and maintained as "prisoners" in a combination of electric and magnetic fields. Thus the material before the resulting annihilation is captured by the detector.

This annihilation is one of the great mysteries of the Big Bang that scientists try to answer (the conversion of antimatter to matter in this dominance).

This antimatter can not be used as energy or weapon because it requires a lot of energy to produce it. To have an idea, we use the following example: Let's try to create 0.5 g of antimatter. Therefore, it is necessary 22 kton (kilo ton) of TNT (approximately the same as Hiroshima's bomb) to produce a half gram of matter and antimatter. The energy associated with 0.5 g of antimatter is 4,5 x 1013 J.The total energy required (efficiency ~10-9 %) would be 4,5 x 1022 J.Even with the CERN discount given by the French electricity company [1 kWh = 3.6 x 106 J = 0.1 €], the cost would be 1 x 108 € and would take one billion years deliver it.

Finally, it should be noted that antimatter is used in the body, where a proton is replaced by a positron in the glucose molecule to be detected by PET (Positron Emission Tomography) used in medicine. The next step for the scientists will be create a therapy using positrons.